diff --git a/src/gamedata/a_weapons.cpp b/src/gamedata/a_weapons.cpp
index fe5761222..c2840ca28 100644
--- a/src/gamedata/a_weapons.cpp
+++ b/src/gamedata/a_weapons.cpp
@@ -544,6 +544,9 @@ int FWeaponSlots::RestoreSlots(FConfigFile *config, const char *section)
 //
 //===========================================================================
 
+// Strict handling of SetSlot and ClearPlayerClasses in KEYCONF
+CVAR(Bool,setslotstrict,true,CVAR_ARCHIVE);
+
 void FWeaponSlots::PrintSettings()
 {
 	for (int i = 1; i <= NUM_WEAPON_SLOTS; ++i)
@@ -589,7 +592,12 @@ CCMD (setslot)
 	}
 	else if (PlayingKeyConf != nullptr)
 	{
-		PlayingKeyConf->ClearSlot(slot);
+		// Only clear the slot first if setslotstrict is true
+		// If not, we'll just add to the slot without clearing it
+		if(setslotstrict)
+		{
+			PlayingKeyConf->ClearSlot(slot);
+		}
 		for (int i = 2; i < argv.argc(); ++i)
 		{
 			PlayingKeyConf->AddWeapon(slot, argv[i]);
diff --git a/src/gamedata/keysections.cpp b/src/gamedata/keysections.cpp
index 7076ebbaa..16d2a7920 100644
--- a/src/gamedata/keysections.cpp
+++ b/src/gamedata/keysections.cpp
@@ -223,11 +223,45 @@ void D_LoadWadSettings ()
 	ParsingKeyConf = false;
 }
 
+// Strict handling of SetSlot and ClearPlayerClasses in KEYCONF (see a_weapons.cpp)
+EXTERN_CVAR (Bool, setslotstrict)
+
+// Specifically hunt for and remove IWAD playerclasses
+void ClearIWADPlayerClasses (PClassActor *ti)
+{
+	for(unsigned i=0; i < PlayerClasses.Size(); i++)
+	{
+		if(PlayerClasses[i].Type==ti)
+		{
+			for(unsigned j = i; j < PlayerClasses.Size()-1; j++)
+			{
+				PlayerClasses[j] = PlayerClasses[j+1];
+			}
+			PlayerClasses.Pop();
+		}
+	}
+}
+
 CCMD(clearplayerclasses)
 {
 	if (ParsingKeyConf)
-	{
-		PlayerClasses.Clear();
+	{	
+		// Only clear the playerclasses first if setslotstrict is true
+		// If not, we'll only remove the IWAD playerclasses
+		if(setslotstrict)
+			PlayerClasses.Clear();
+		else
+		{
+			// I wish I had a better way to pick out IWAD playerclasses
+			// without having to explicitly name them here...
+			ClearIWADPlayerClasses(PClass::FindActor("DoomPlayer"));
+			ClearIWADPlayerClasses(PClass::FindActor("HereticPlayer"));
+			ClearIWADPlayerClasses(PClass::FindActor("StrifePlayer"));
+			ClearIWADPlayerClasses(PClass::FindActor("FighterPlayer"));
+			ClearIWADPlayerClasses(PClass::FindActor("ClericPlayer"));
+			ClearIWADPlayerClasses(PClass::FindActor("MagePlayer"));
+			ClearIWADPlayerClasses(PClass::FindActor("ChexPlayer"));
+		}
 	}
 }
 
diff --git a/wadsrc/static/menudef.txt b/wadsrc/static/menudef.txt
index d4d325e05..216791854 100644
--- a/wadsrc/static/menudef.txt
+++ b/wadsrc/static/menudef.txt
@@ -1198,6 +1198,7 @@ OptionMenu "MiscOptions" protected
 	Option "$MISCMNU_QUICKSAVEROTATION",			"quicksaverotation", "OnOff"
 	Slider "$MISCMNU_QUICKSAVECOUNT",			"quicksaverotationcount", 1, 20, 1, 0
 	Option "$MISCMNU_DEHLOAD",					"dehload", "dehopt"
+	Option "$MISCMNU_SETSLOTSTRICT",			"setslotstrict", "YesNo"
 	Option "$MISCMNU_ENABLESCRIPTSCREENSHOTS",		"enablescriptscreenshot", "OnOff"
 	Option "$MISCMNU_INTERSCROLL",				"nointerscrollabort", "OffOn"
 	StaticText " "